Large pipelines typically include a plurality of flanged pipes joined to one another by bolts which pass through the flanges and hold the flanges together. Similarly, components such as valves, pumps and the like are often provided in the pipeline and they also have matching flanges which are joined to the pipe flanges in the same manner. Maintenance and servicing of a pipeline and its components often requires removal and replacement of a length of pipe or a component. It will be appreciated that removal of lengths of pipe or components can be difficult with large pipelines especially where the pipeline is underground or held in place by steel or concrete structures so that the pipeline cannot be axially or laterally moved. Such pipelines generally include dismantling joints between selected pipes or selected components which can be shortened for installation and removal and lengthened once in place to close the gap between the adjacent pipe flanges or component flanges as the case may be.
The presently known dismantling joints typically include two telescoping pipe or tube portions with flanges which correspond in size to the pipe flanges and they are held in place by bolts which pass through the adjacent pipe flanges (or component flanges) and through the corresponding flanges of the dismantling joint.
That arrangement can result in bending of the pipe flanges, known as “flange rotation” (a type of “cupping” of the adjacent flanges in the axial direction). Consequently, dismantling joints have require undesirably large heavy flanges to carry the applied loads.
Moreover, the removal or replacement of an existing dismantling joint is complicated and time-consuming because it is necessary to remove all of the tie-bolts that are used to secure the dismantling joint to adjacent pipeline components before the dismantling joint can be removed or replaced. Access to the nuts and/or bolts also requires dismantling joints to be undesirably long in the axial direction.
Additionally, when a dismantling joint is installed, there could be some misalignment between the faces of the flanges of the dismantling joint and the mating faces of the adjacent flanges of the pipeline. In existing arrangements, such misalignment is normally taken up by gaskets, but this approach is known to produce an inferior seal for the joint structurally and from the aspect of seal integrity.
The present invention is aimed at ameliorating at least one of the problems of presently known dismantling joints. The invention is also aimed at providing a dismantling joint which is reliable and efficient in use.
With the foregoing in view the present invention, in one aspect, resides broadly in a dismantling joint for joining a first pipeline component to a second pipeline component, the first and second pipeline components being connectable to one another along a common axis by a plurality of connectors spaced from the axis and each pipeline component having a sealing face opposed to the other, the dismantling joint including:                a first half and a second half, each half having a central axis, and the first half including a cylindrical spigot having an outer face and a flange extending outwardly from the outer face of the spigot, the flange having an inner face and an outer face remote from the inner face, and the second half including a socket adapted to slidably receive therein the spigot of the first half, the socket having a proximal end and a distal end remote from the proximal end, the proximal end being opposed to the inner face of the flange of the first half; and        forcing means arranged between the inner face of the flange of the first half and the proximal end of the spigot to engage the inner face of the flange of the first half and the proximal end of the socket of the Second half adjacent the outer face of the spigot to force the first and second halves away from each other and into sealing engagement with the sealing faces of the pipeline components, and wherein        
the forcing means is arranged about a pitch circle spaced from the central axes such that the spacing of the pitch circle is less than the spacing of the connectors when the central axes of the dismantling joint are aligned with the common axis of the pipeline components.
In another aspect, the present invention resides broadly in a dismantling joint for joining a first pipeline component to a second pipeline component, the first and second pipeline components being connectable to one another along a common axis by a plurality of connectors spaced from the axis and each pipeline component having a sealing face opposed to the other, the dismantling joint including:                a first half and a second half, each half having a central axis, and the first half including a cylindrical spigot and a flange extending outwardly therefrom, the flange having an inner end and an outer end remote from the inner end, the second half including a socket adapted to slidably receive the spigot of the first half, the socket having a proximal end and a distal end remote from the proximal end, the proximal end being opposed to the inner end of the flange of the first half; and        forcing means arranged to engage the inner end of the flange of the first half and the proximal end of the socket of the second half adjacent the outer face of the spigot to force the first and second halves away from each other and into sealing engagement with the sealing faces of the pipeline components, and wherein        
the forcing means is arranged about a pitch circle spaced from the central axes such that the spacing of the pitch circle is less than the spacing of the connectors when the central axes of the dismantling joint are aligned with the common axis of the pipeline components.
Preferably, the forcing means includes a plurality of bolts or screws each threadedly engaged with a threaded passage extending axially through either the flange or the socket such that the head of each bolt or screw abuts the other one of the proximal end or inner face respectively. However, it will be appreciated that the forcing means may take other forms, such as, but not limited to, a plurality of rods which extend between the inner end of the flange of the first half and the proximal end of the socket of the second half, each rod having location means for locating the rods in a radially and circumferentially fixed position with respect to both the flange and socket, and each rod further having threaded portions upon which two nuts are threadedly engaged to be wound away from one another against the inner end of the flange and the proximal end of the socket. The bolts or screws are arranged in circumferentially spaced disposition adjacent the outer face of the spigot, meaning relatively close to the outer face and such that the axial compressive force is exerted close to, or even in substantial alignment with, the pipe wall or equivalent thereto of the pipeline components being joined to one another. By being joined to one another, it will be appreciated that the pipeline components are joined in axially spaced disposition with the dismantling joint interposed between them.
It will be seen that the axial or longitudinal compressive force of the forcing means is directed against the flanges of the pipeline components at each end of the dismantling joint, the compressive force being taken up by tie bolts joining the pipeline components to one another.
In another aspect, the present, invention resides broadly in a dismantling joint for interposition between a first pipeline component and a second pipeline, component joined to one another by pipeline fasteners, the first and second pipeline components being connectable to one another along a common axis by a plurality of connectors spaced from the axis and each pipeline component having a sealing face opposed to the other, the dismantling joint including:                a flanged spigot having a central axis and a flange and a spigot having an internal passage extending therethrough;        a flange adaptor having a central axis and an internal bore for receiving the spigot;        sealing means interposed between the flange and the flange adaptor for sealing against fluid flow from the internal passage of the flanged spigot;        compression means adapted for interposition between the flange of the flanged spigot and the flange adaptor, the compression means, being operable to impart an axial compressive load therebetween; and wherein        the flange and the flange adaptor are adapted to function independently of the pipeline fasteners and into sealing engagement with the sealing faces of the pipeline components, and wherein        
the compression means is arranged about a pitch circle spaced from the central axes such that the spacing of the pitch circle is less than the spacing of the connectors when the central axes of the dismantling joint are aligned with the common axis of the pipeline components.
In another aspect, the present invention resides broadly in a method of dismantlably joining a first pipeline component to a second pipeline component by pipeline fasteners including:                providing a flanged spigot having a flange and a spigot having an internal passage extending therethrough;        receiving an end of the flange remote from the flange into an internal bore of a flange adaptor;        sealing the flange adaptor and flange against fluid flow from the internal passage of the flanged spigot to provide an axially expansible flanged assembly;        operatively interposing the flanged assembly between the flanges of the first and second flanged components; and        imparting an axial compressive load between the flange and the flange adaptor independently of the pipeline fasteners.        
Preferably, the flange and spigot of the first half are integrally formed and may be in the form of the flanged spigot hereinbefore described. It is also preferred that the flange is at or near one end of the spigot. However, it will be appreciated that the flange and spigot may be separate components having sealing means operatively interposed between the components to seal against fluid flow from the internal passage through the spigot, that is, providing a sealing between the flange and the cylindrical outer face of the spigot.
Preferably, the sealing means includes a seal and a follower for pressing the seal against the spigot and the flange adaptor. In such form, the follower is in the form of a ring having dimensions substantially commensurate with the dimensions of the flange adaptor.
Preferably, the compression means includes a plurality of threaded rods and complementary threaded apertures extending axially into or through either, ox both the flange and the flange adaptor. In a preferred form, the threaded rods are provided in the form of bolts having a threaded portion, a non-threaded portion extending axially from the threaded portion and a compression face on the end of the non-threaded portion remote from the threaded portion. The non-threaded portion suitably includes two or more engagement faces for operable association with a wrench or the like far turning the bolts about their axes. Preferably, the compression faces of the bolts are domed to a degree sufficient to permit engagement with a bearing face of the follower substantially centrally of the compression faces notwithstanding engagement with the bearing faces at an angle slightly off perpendicular.
It will be seen that the compressive load may be imparted by turning the bolts in a direction which unscrews them from the complementary apertures in or through the flange and/or flange adaptor. Preferably, a lock nut is provided on each bolt for locking against rotation of the bolt once the desired compressive load has been provided by the unscrewing of the bolts.
The flange adaptor may include a rebate or groove for receiving the seal. Preferably, the dismantling joint includes a seal containment ring that surrounds the seal. In a preferred form, the follower includes a plurality of threaded holes. A relief ring may also be provided for operable interposition between the flange adaptor and the seal containment ring. The relief ring includes a plurality of clearance holes sized to permit axial penetration of the bolts therethrough, it being preferred that the clearance holes in the relief ring extend longitudinally all of the way through the relief ring. It is also preferred that the follower further includes a seal backing plate ring located between the relief ring and the flange adaptor.
Alternatively, the follower includes a plurality of apertures, each of which has a threaded portion and an unthreaded clearance portion. It is also preferred that the apertures extend longitudinally all of the way through the follower. It will be appreciated that the threaded apertures may be provided in an alternative form by incorporating a captured nut in a clearance aperture for each or any one of the threaded apertures.
The first and second flanged components may be selected from a pipeline, a valve, a pump, a joint or the like. Moreover, the flanged spigot or the flange adaptor may be incorporated into one end of a pipeline fitting such as a pump, valve, joint or the like to enable the fitting to be removed from the pipeline in similar manner to having the dismantling joint hereinbefore described provided separately in axial interposition between a pipeline flange and a flange on the pipeline fitting.
In another aspect, the present invention resides broadly in a dismantling joint for joining a first pipeline component to a second pipeline component, the first and second pipeline components being connectable to one another along a common axis by a plurality of connectors spaced from the axis and each pipeline component having a sealing face opposed to the other, the dismantling joint including:                a flanged spigot;        a flange adaptor that receives the flanged spigot;        a seal for sealing between the flanged spigot and the flange adaptor;        a follower for pressing the seal against the flanged spigot and the flange adaptor; and                    a plurality of bolts spaced about a central axis and screwed into a plurality of threaded holes such that the bolts extend longitudinally between the flanged spigot and the follower such that the bolts are able to be partially unscrewed so that they are thereby able to move the flanged spigot and the follower away from each other so that the flanged spigot is able to press a first gasket against the first pipeline component, the flange adaptor is able to press a second gasket against the second pipeline component, and so that the follower is able to press the seal against the flanged spigot and the flange adaptor, and so that the flanged spigot and flange adaptor may be pressed into sealing engagement with the sealing faces of the pipeline components, and wherein                        the bolts are arranged about a pitch circle spaced from the central axis such that the radius of the pitch circle is less than the spacing of the connectors from the common axis when the central axis of the dismantling joint is aligned with the common axis of the pipeline components.        